The present invention relates to clamps that allow vibratory devices to be attached to elongate members and, more particularly, such clamps that are adapted to grip generally cylindrically-shaped piles of wood and/or concrete.
In the construction industry, it is often necessary to insert piles into and withdraw piles from the earth. A common scenario is the removal of wooden piles and the replacement of these wooden piles with concrete piles.
To insert piles into and remove piles from the earth, a large driving or pulling force must be applied to the pile. Often, vibratory devices are employed to introduce a vibratory force along the axis of the pile during the process of driving or pulling the pile. The combination of a static pulling or driving force with a vibratory or dynamic force is usually sufficient to overcome the earth""s resistance and allow the pile to be inserted or withdrawn.
In cases where the pile is being withdrawn from the earth and/or a vibratory force is being applied, a clamping assembly must be provided to allow a pulling force and/or vibratory forces to be effectively transmitted to the pile. Such clamping devices have heretofore comprised a housing that is attached to a vibratory hammer which in turn is suspended from a crane line and/or vibratory device, a first gripping surface securely attached to the housing, a second gripping surface connected to a pivot arm that is rotatably attached to the housing, and a piston actuator that acts on the pivot arm to force the second gripping surface against the first gripping surface.
Accordingly, to connect a pile to a vibratory device or tensioning cable, the piston actuator is retracted to create a gap between the first and second gripping surfaces. The pile is then inserted between the first and second gripping surfaces and the piston actuator extended such that the pile is gripped between the first and second gripping surfaces. The pile is thus fixed relative to the housing, and the housing itself can be attached to the vibratory device or tensioning cable.
Users have experienced a variety of problems with such prior art clamping assemblies. For example, because piles, especially wooden piles, are often of irregular shapes and sizes, the gripping surfaces do not engage certain of these piles in a manner that effectively transmits tensioning or vibratory loads thereto. This allows the pile to slip within the clamping assembly. This is especially true when the piles are coated with barnacles or other materials that reduce friction between the gripping surfaces and the pile.
Slippage of the pile relative to the clamping assembly lessens the effectiveness of the clamping assembly at transmitting loads to the pile. Further, during insertion of the pile, such slippage can result in the pile moving upward relative to the clamping assembly housing and contacting an upper wall of this housing. Then, as further driving and/or vibratory forces are applied to the pile, the pile batters the upper wall of the housing. This can cause damage to the clamping assembly housing itself, to the assembly by which the housing is attached to the vibratory device or tensioning cable, and to the machined surfaces on the vibratory device.
Another problem with the prior art clamping assemblies is that bolts used to attach the housing thereof to a vibratory device must be installed from within the housing. This is an awkward and time consuming process and exposes the mounting bolts to the impact of the pile.
Yet another problem with prior art clamping assemblies is that, because different gripping surfaces are required for different types of piles, a different clamping assembly is required for each of the types of piles that will be driven or pulled. This is especially a problem in cases where wooden piles are being removed and replaced with more permanent piles such as concrete or steel. In this situation, the entire clamping assembly must be removed from the vibratory device between the removal of one pile and the insertion of another.
From the following discussion, it will be apparent that these and other problems with prior art clamping assemblies are solved by the present invention.
The Applicant is aware of the following clamp assemblies for connecting pulling and vibratory devices to a pile to be inserted or extracted.
International Construction Equipment has for several years sold products identified as a Model 70 Pile Clamp and a Model 50 Pile Clamp. Both of these pile clamps have one fixed jaw and one movable jaw. In the Model 70 Pile Clamp, the actuator and pivot point of the movable jaw are arranged on the same side of the pile. With the Model 50 Pile Clamp, the actuator and pivot point of the movable jaw are arranged on opposite sides of the pile.
The Assignee of the present application is also the assignee of U.S. Pat. No. 5,609,380. The ""380 patent discloses a clamp assembly having a fixed jaw and a movable jaw. An actuator is operatively connected to the movable jaw such that extension of the actuator causes the movable jaw to move towards the fixed jaw. In the device described in the ""380 patent, the movable jaw is pivotably connected to the housing at a pivot point that is arranged on an opposite side of the pile than the side on which the movable jaw is arranged. This arrangement allows the device to be more compact and allows the center of gravity of the clamp assembly to be more aligned with the longitudinal axis of the pile.
U.S. Pat. No. 3,998,063 discloses a pile driving/pulling system comprising one fixed shoe and one movable shoe for gripping the pile.
U.S. Pat. No. 4,195,698 discloses a driving/pulling system having fixed teeth and movable holding teeth formed on a movable holding teeth member.
U.S. Pat. No. 4,180,047 discloses a pile cutting apparatus and system that comprises gripping clamp means for gripping a pile at locations above and below the cut. Eight of these gripping clamp means are located above the cut line. Each of these upper gripping clamp means comprises a dog with gripping teeth formed thereon. The dogs are rotatably connected to a structural member such that the operation of a hydraulic ram forces the gripping teeth against the pile being cut.
U.S. Pat. No. 4,018,290 discloses a hydraulically driven vibrator for driving and/or extracting sheet piles having a pair of clamping jaws. One of these clamping jaws is fixed, and the other is connected to an actuator and pivotably attached to the vibrator housing. Operation of the actuator causes the movable jaw to move towards the fixed jaw to clamp the sheet pile.
U.S. Pat. No. 4,099,387 to Frederick et al. appears to disclose a clamp for driving sheet piles having one fixed jaw portion and a movable jaw or piston that grips the pile against the fixed jaw portion.
U.S. Pat. No. 3,243,190 discloses a vibratory pile driver having a clamp assembly comprising one fixed and one movable jaw.
U.S. Pat. No. 3,243,190 discloses a vibratory pile-driver having a clamp assembly composing one fixed-and-on movable jaw.
U.S. Pat. No. 4,248,550 discloses a clamping mechanism for extracting piles that uses opposing, movable gripping members connected to the clamp housing. The gripping members are connected to a housing using a parallelogram linkage that causes the gripping members to engage the pile when the housing is lifted and disengage the pile when the housing is dropped.
U.S. Pat. No. 3,828,864 discloses a vibratory pile extractor having first and second jaw members. The jaw members receive the pile, and a piston actuator is operated to force the pile against one of the jaw members.
U.S. Pat. No. 5,263,544 to White discloses a shock absorbing apparatus, or suppressor, for use with vibratory pile drivers/extractors.
European Patent Application No. 89830412.6 discloses a vibratory device for drilling machines comprising a double vice arrangement for clamping the vibratory device to the drilling machine.
From the foregoing, it should be clear that one primary object of the present invention is to provide improved clamping systems and methods for securely attaching a pile to a vibratory device or the like.
A further object of the invention is to provide a clamp assembly having a favorable combination of the following characteristics:
(a) allows vibratory forces to be applied substantially along the longitudinal axis of the pile being driven/extracted;
(b) reduces slippage of the pile relative to the clamp assembly;
(c) improved pile driving ability;
(d) reduction of damage to clamp assembly, connecting assembly, and vibratory device should slippage of the pile relative to the clamp assembly occur;
(e) easier attachment of the clamp assembly to the vibratory device;
(f) allows a quick and easy change from gripping one pile type to gripping another pile type; and
(g) allows the operator of the pile driving and/or pulling equipment to view the operation of the gripping assembly and the activities of workers on the other side of the pile.
As will become clear from the following detailed discussion, these and other objects are achieved by the pile clamp system of the present invention.
The present invention is a clamping assembly for use in a pile driving and/or removing system that allows a vibratory device to be securely affixed to a pile. The clamping assembly comprises first and second gripping assemblies arranged on either side of the pile. Each gripping assembly is mounted on a pivot arm assembly such that rotation of the pivot arm assembly relative to a housing of the clamp assembly causes the gripping assemblies to engage the pile. Actuator assemblies are rotatably connected to the housing and the pivot arm assemblies such that extension and retraction of the actuator assemblies cause the gripping assemblies to move between an open configuration and a close configuration.
The gripping assemblies, pivot arm assemblies, and actuator assemblies are substantially the same and arranged on opposing sides of the pile such that a center of gravity of the clamping assembly is aligned with a center of gravity of the pile.
In addition, the movement of the gripping assemblies is coordinated such that these gripping assemblies move between the open and close configurations in synchrony with each other. This may be obtained by synchronizing the action of the actuator assemblies used to move the pivot arm assemblies. Preferably, however, this synchronization is obtained by the use of gear members operatively connected to the gripping assemblies. These gear members extend on either side of the pile and engage each other such that synchronized movement of the gripping assemblies is mechanically obtained. The gear members are also symmetrically arranged about the longitudinal axis of the pile to ensure that the center of gravity of the clamping assembly is substantially aligned with the longitudinal axis of the pile being clamped.
The gear members have teeth formed thereon in first and second sets that are offset from each other such that the angular displacement of the pivot arm assemblies relative to horizontal is always the same. The teeth on the gear members extend through an arc of approximately 75 degrees in a circle centered on the longitudinal axis of pivot pins used to attach the pivot arm assemblies to the housing.
The housing is a rigid structure having an upper wall connected to a mounting plate by a vertical plate and a plurality of bracing plates. The top wall, vertical plate, bracing plates, and mounting plate form an anvil that engages and drives the pile should slippage between the pile and gripping assemblies occur.
The housing is configured such that pivot and hinge pins used to attach the pivot arm assemblies and actuator assemblies to the housing are accessible at all times. In addition, openings are formed in the housing such that actuator pins that connect the actuator assemblies to the pivot arm assemblies are accessible when the gripping assemblies are in their open configuration. Similarly, additional openings are formed in the housing such that actuator pins that connect the actuator assemblies to the pivot arm assemblies are accessible when the gripping assemblies are in their closed configuration. The entire clamping assembly thus may be easily assembled and disassembled for manufacture, repair, and maintenance.
The clamping assembly of the present invention obtains the objects described above as well as other objects as will become apparent from a review of the following detailed description.